This project will continue to explore interactions between immunoglobulins and tissue cells in a number of different disease states. Particular attention will be directed at studies of lymphocytophilic antibodies and lymphocytotoxic antibodies in the connective tissue diseases. Lymphocytotoxic antibody with specificity for T cells will be studied. In addition, studies of the phagocytic mechanism involved in opsonization of pneumococci will be carried out.